Background: National Asthma Education and Prevention Program (NAEPP) guidelines exist, but are underused in primary care. In addition, implementation of guidelines has been shown to vary according to location of practice and other contextual factors. Objective: The Children's Hospital of Philadelphia Pediatric Research Consortium (PeRC), a practice-based research network will determine whether an innovative clinical decision support system embedded in an existing electronic health record (EHR) will improve provider adherence to the existing NAEPP guidelines. Methods: After receiving a standardized education module based on NAEPP guidelines, 10 primary care pediatric practices (both urban and suburban sites) will be randomized to receive either a passive EHR (control sites) or an interactive decision support system (intervention sites). The primary outcome of interest will be the proportion of patients on appropriate asthma controller medication compared over time. Secondary outcomes include the proportion of asthma patients with: 1) an updated asthma action plan, 2) documentation of spirometry performed (6 to 17 yrs.) and 3) an updated problem list reflecting current asthma severity. After hours calls to providers and types of office visits related to asthma will be tracked. Contextual factors at the clinic and patient level will be examined to assess their association with outcomes of interest. In addition, measurement of asthma-related quality of life and missed school and work in a sample of 200 subjects from each group will be performed. If shown to be successful, this type of clinical decision support, embedded within the EHR, has the potential to be a powerful tool to improve the implementation of asthma guidelines and clinical practice guidelines for other conditions and illnesses.